The present invention relates generally to hydraulic systems and pertains particularly to the lubricating and damping system for a mechanically driven impact rock breaker.
Many mechanically driven apparatus such as the rock breaker disclosed in U.S. Pat. No. 3,868,145, issued Feb. 25, 1974 to Cobb et al and assigned to the assignee hereof employ mechanical mechanisms which are orientable into a number of different positions. These mechanical apparatus require continuous lubrication of bearings or the like to prevent failure. If the lubricating system is self-contained, it must be capable of properly functioning in many different orientations of the mechanism.
Preferably the lubricating fluid is circulated within the system to enhance the lubrication of the bearings as well as for filtering and cooling the lubricating fluid as well as assisting in cooling the machine. The lubricating system circulating path will normally have a volume exceeding that of the volume of lubricating fluid therein. Thus, a large volume of air will fill the spaces not taken up by the oil. For this reason, when the mechanism undergoes various orientations one or more inlets to its circulating pumps may not be submerged in oil and the pump may take in a volume of air.
In order to insure proper lubrication, it is essential that a continuous flow of lubricating oil itself be supplied under pressure to the bearings within the system. Should sufficient air get within the oil, the supply of oil to the bearings can become interrupted, thus, resulting in damage to the bearings of the system.
In order to maintain an oil flow, the pump or pumps must continuously draw in a quantity of oil from the sump or reservoir. Since the oil will always flow to the lowest side of the reservoir when the machine is tilted in any one of a number of operating positions, the oil will flow to the low side at that one position. Thus, an inlet to a pump must always be submerged in the oil in order to draw in a supply of oil. If a plurality of inlets are used, it is likely that one or more of the inlets will become open to the volume of air over the oil in the tank from time to time during operation of the machine. Thus, the pump having such an inlet open to the air will draw air into the pump resulting in a mixing of the air with the oil within the system.